A method for growing a silicon single crystal includes determining a diameter to give the maximum value of a ratio of an equivalent stress and a critical resolved shear stress in a tail portion on the occasion of the gradual cooling of the silicon single crystal in an after-heating step, in advance; wherein, the tail portion is grown in the tail forming step under a condition that an interstitial oxygen concentration at a position of the determined diameter is 8.8×1017 atoms/cm3 (ASTM '79) or more. This method for growing a silicon single crystal by a CZ method can efficiently grow a heavy weight and large-diameter silicon single crystal while suppressing a generation of slip dislocations in the tail portion of the silicon single crystal in the after-heating step to gradually cool the crystal after finishing the tail forming step.